Palladium-catalysed cross-coupling of a new umpolung reagent, (α-methoxy-γ-tributylstannyl)allyltrimethyl-silane, with acyl or aryl halides, involves exclusively the vinyl–tin bond and subsequent desilylation with tetrabutylammonium fluoride gives enol ethers, precursors of β-acyl- or β-aryl-propionaldehydes.